I find it very distracting the way the search bar changes size when I start typing in the search box. On my monitor my input cursor is at around pixel X of around 1200 when I start typing but then the input cursor suddenly jumps to around pixel X 900 as it expands. It's an 'uncomfortable' feeling, on a site that is otherwise super comfy, as I have to adjust my eye focus point.

I'm sure some people love it but I'd rather have a button that I can click to expand the field when I want it resized rather than it happen automatically.